Composite wire for spraying a nondrawable metal



Patented Oct. 9, 1951 COMPOSITE WIRE FOR SPRAYING A NONDRAWABLE METAL Charles Davidoif, New York, N. Y., assignor to Metallizing Engineering Co. Inc., Long Island City, N. Y., a corporation of New Jersey No Drawing. Application March 27, 1948, Serial No. 17,593

7 Claims.

This invention relates to new and useful immovements-in composite wires for spraying heatfusible, materials, and is a continuation in part of my abandoned application Serial Number 672,914, filedMay 28,, 19,46. 7

the art of spraying heat-fusible materials, such as metals, plastics or the like, the material to. be sprayed is fed in; the. form of a wire or rod into. a melting zone. The advancing tip of the wire or rod is melted inthis zone and the molten material is atomized'by a blast of air or other gas, the. atomized material being propelled by the air or gas blast onto the object to be coated. The

-' spraying operation is. usually performed with the taid of. what is termed a spray gun of the wire feed Many of the; heatrfusible materials, do not readily lend themselves tobe sprayed in wire or rod form. Also many of. these materials are not adapted. to be fabricated into wire or rod form and thus are incapable of use in heat-fusible maeri l sp ay u s of thewi e. teed; ime Fu the mo e, ce ta n. heat-fu ible m als s. u h are not sufliciently flexible to be; made into wire that can. be coiled. They are, for this reason, unecoii mi a in thei pp ca ion sin e ey can h onlybfi; us d in the form of relatively short lengths 01: wire or rod necessitating frequent interruption of the spraying operation in order to supply the gun. with a new len th of wire or rod whe ever the preceding one is used up in the spray n Operation. Also, certain heat-fusible materials and particularly a number of the metals or metal alloys; can be frabricated only with diflicultyinwire on rod form and only at considtab exp nse rende in th ir use. for sprayin operations in a. wire. feedtypespraygun relativeis cost y and: un e emiea It is also. some es e irable. to ray certain mixtures of heatef-usible material with other agentsas, for instflnqel mixtures of metal with 16 aetory materials, metalloids, minerals or the lik in order toobtain sprayed coatings of such tures. Wires; or rQdsof heat-fusible material, hpweyep are normallyonly available as unitary materials; for-example in the; case of metals they are a ai able i h r'i he r f the. m t l as e the form o i l e or the e a l'urgically uniform product.

Qne. object of the invention is, inter alia, a wire for spraying in a gun of. the-wire feed type, comprising a, heat-fusible, material which does not mails; lend itself r adi y ois rav ne in r or term. Am her bj ct, of. t n e i n. ce

aiW IQ. which can be fabricated. using 2 any heat-fusible material including any that as such. cannot be normally made into wire or red form.

A further object of the invention comprises such a wire which can be fabricated using a heat.- fusible material that is normally difficult or expensive to makeinto wire form.

A further object of the invention comprises such a wire which is sufficiently flexible to, be coiled though containing heat-fusible material normally as such of insufficient flexibility to be coiled when in wire or rod form.

A still further obj ectv of the invention comprises such a wire adapted to spray composite coatings containing heat-fusible material in mixture with other materials, including refractory materials, fillers, binders, metals, metalloids, minerals, agents for modifying the characteristics of the sprayed coatings and/or any other suitable or desirable. material or agent.

The foregoing and still further objects of the invention will appear from the following description:

It has been proposed in the past to prepare composite wires of ordinarily non-.drawable metals by the use of agglutinants, such as glue,

rubber. and benzol, water glass or dextrin. Composites of this type, however, are useful only in connection withthe preparation of relatively thin decorative or corrosion, protective coatings. The

aglutinants give rise to the formation of decomposition, products that, are carried into the sprayed metal layer contaminating the same to the point where they interfere with the strength and bonding characteristics of these coatings. Such type composites cannot be used for the application of spray metal coatings; built up to any appreciablethickness, and particularly those used in the repair or rebuilding of machine elements in which considerable stresses and strains have tobeborne by the applied spray metal. .In addition to the aforementioned objects, it is a further and important object of this invention to tion to obtain spray metal coatings on hard facing alloys substantially free from contaminating materials, even though the metal wire or rod used in their application is a composite containing a binder material.

Applicant has discovered certain types of binder material which, notwithstanding the very high temperatures maintaining in the melting zone of heat-fusible material spray guns, are removed from the metal sprayed such as by volatilization to an extent where the products per se or in some converted form are eliminated from the sprayed particle stream so that the coatings obtained are not contaminated by any binding material or decomposition products thereof.

The composite wire in accordance with the invention comprises a heat-fusible material in substantially subdivided form mixed with and held to shape by a plastic binder material which is substantially removable by heat at not in excess of the highest temperature of the liquid phase temperature range of said heat-fusible material.

The term liquid phase temperature range as used herein in connection with a heat-fusible material is intended to designate that temperature range within which said heat-fusible material is in substantially heat liquefied condition with a limiting low temperature at which heat softening of said material occurs and a limiting top temperature above which vaporization or destruction of said material occurs.

The plastic binder material used in accordance with the invention may be any plastic binder material imparting to the composite product the capacity of being shaped into rod or wire form in the making of the composite wire in accordance with the invention, provided, however, that the plastic binder material shall be substantially completely eliminatable by heat at a temperature above room temperature and not in excess of the liquid phase temperature range of the heat-fusible material. Elimination at said temperature may be volatilization, partial destruction, oxidation or other reaction, gas blast dispersion, atomization or otherwise. Suitable plastic binder materials are, for instance, cellulose base solventsetting plastics, thermo-setting and thermoplastic plastics. Cellulose base solvent-setting plastics, i.e., plastics which set into shape from solvent solutions, such as by precipitation or solvent evaporation or other solvent removal, are, for instance, of the type including solvent solutions such as acetone-, amyl acetate-, diethylene glycol-, diethylene glycol alkyl esters, or the like solutions of cellulose, cellulose esters or ethers well known in the art. Thermo-setting and thermoplastic plastics may be of the type including phenolformaldehyde resins, urea-formaldehyde resins, polystyrenes, thermoplastic cellulose esters, thermoplastic polymerized vinyl esters and the like. It is preferred, however, to use one or more of the thermoplastic binder materials of the described characteristics and particularly of the type possessing a volatilization or vaporization point not in excess of the highest temperature of the liquid phase temperature range of the heatfusible material and preferably at the softening or the melting temperature thereof. Preferred thermoplastic materials are, for instance, exemplified by polyethylene, dioctyl phthalate, polystyrene, cellulose acetate, copolymer of vinyl acetate and vinyl chloride or the like.

In preparing the composite Wire in accordance with the invention, the heat-fusible material is thoroughly mixed in a suitable form, preferably finely subdivided such as powder or granules, with the plastic binder material.

The invention is particularly useful in connection with composite wires in which metal constitutes the heat-fusible material. Wherever the word metal is used herein in designation of a heat-fusible material in accordance with the invention, the same is intended to include both pure metals as well as alloys.

The preferred embodiment of my invention is a composite wire comprising a metal powder bound together by a thermoplastic material which is substantially eliminatable by heat not in excess of the liquid phase temperature of the metal.

Within the preferred embodiment of my invention, any metal may be used which may be handled as a powder or in finely granulated or other suitably subdivided form in a stable state, and my invention is particularly useful in connection with normally brittle metals such as chromium, chromium iron alloys, nickel-boron-chromium alloys, or others which, because of their brittleness, cannot be fabricated into solid rods or wire.

The thermoplastic material that may be used within the preferred embodiment of my invention is one which is sufficiently eliminatable by the heat of the heating zone of a heat-fusible material spray gun of the gas blast wire feed type to permit the complete removal by release of the metal particles to be propelled from the heating zone by the gas blast. The thermoplastic binder materials should be substantially com pletely eliminatable by the heat of the heating zone of such gun so as to avoid to the largest extent possible contamination (with plastic material) of the ultimate spray metal coating on the object sprayed. For this reason, a thermoplastic material which is substantially volatilized by the heat of the heating zone is the most preferred since the products of volatilization are substantially carried away by the propelling blast of the air or other gas used in the gun and will not therefore contaminate the final spray metal coating. volatilization in this case may be a volatilization or vaporization of the thermoplastic material as such, i. e., solely by reason of a change from solid or liquid to gaseous phase Without substantial decomposition, or, it maybe byway of vaporization by reason of the formation of volatile or gaseous decomposition prod--.

ucts.

Within the general purview of my invention and not necessarily limited to the preferred em-' bodiment thereof, I prefer to use as large a proportion of the heat-fusible material to the plastic binding material as is possible. This proportion depends primarily upon the materials used and it may be necessary to predetermine the requisite proportion for any given combination of materials by simple empirical test. Enough plastic binding material should be used in the mixture to successfully bind together in the composite wire the individual particles of heat-fusible material to yield a wire of sufficient strength and cohesiveness to be readily handled through the feed mechanism of a wire type spray gun for spraying heat-fusible materials.

Depending on the particular plastic binder material used for the fabrication of a composite wire in accordance with the invention, the plastic ma terial may be in the form of a powder, paste, solu' tion or the like. Once the heat-fusible material and plastic binding agent have been thoroughly mixed, the composite wire may be prepared in any number ofdifierent ways well'known in. the. art, such as by casting, pressure molding or extruding, or, molding or extruding with solventevaporation or any other appropriate conventional method. When using a thermoplastic material, it is in most cases preferred touse the same'in finely sub=divided form-suchas-in the form of; granules orpowder. In suchcase, theheat-fusible mate'rial and the thermoplastic; being both; in subdividedform, are'thoroughly mixed and'the mixture is" then subjected to heat so as to convert the mass into 1 mclda-blecondition.

ne'particularlyadvantageous method offabrieating the compositewirein accordance with the invention and using thermoplastic binding. ma: terial is thatof the well known screw typepl'astic extrudihgmachine in which the plastic mix is kneaded under heat and pressure by the action of a screw or worm being at the same time forced forward and through an extruding forming die.

provided with a circular orifice through which the plastic mass is forced in the shape of a wire substantially commensurate in diameter with the orifice of the die.

By way of a further embodiment of my invention, the composite wire may be additionally provided to contain other or auxiliary materials designed to be incorporated into the ultimate sprayed coating with a view of modifying the characteristics thereof. Such other materials may be any one or more selected from a group consisting of refractory. metals, metalloids and minerals. These materials are also added in finely subdivided and preferably powdered form and are bound together with the particles of heat fusible materials to the shape of the composite wire with the aid of the plastic binder material. In such case, when the plastic binder material is reduced and/or eliminated by the heat of the heating or melting zone of the spray gun, the particles of both the heat-fusible material and of the auxiliary agent are sufliciently freed to be expelled by the gas blast of the gun with the heat-fusible material in molten or heat-plastic condition. In this manner, certain desirable properties can be imparted to the sprayed coatings obtained on the objects against which the spray is directed. Thus, for instance, aluminum oxide may be used as a component part of the composite wire imparting extreme hardness and abrasive properties to the sprayed coatings. By way of further example, antimony may be made a component part of the composite wire containing metal as the heat-fusible material, the antimony imparting well known alloying properties in the event that it is desired to heat treat the sprayed metal coating. As a still further example, garnet may be made a component part of the composite wire to change the appearance of the sprayed coatings or to impart thereto properties of wear resistance. In addition to these specific examples, many other agents of the general type of refractory metals, metalloids and minerals may be incorporated as component of the composite wire in accordance with the invention, either alone or in mixture with each other.

It is further possible within the scope of the invention to so compose the novel composite wire that substantially non-oxidizing and even reducing conditions are created to assure the spraying of the heat-fusible material with as little oxidation as possible. This is particularly desirable in the spraying of metals. Thus, the composite wire may be made to generate an inert gas, as,

ammo-4a forinstance; when selectingas the binder ma-.- terial any organic and particularly cellulosic ma-. terial at l'east -to alarge extent reducible by the heat of the metal: spray gun to CO and. H2. Alternatively, CO, Hz, Ne generating materials: or suitable deoxi'di'zers such as-ferroalloys. of manganese, siliconandtitanium may be incorporated in th e compo'site wire inaddition to the plastic binder and/or in lieu of the aforementioned auxiliary materials.

The following examplesare furnished by way of illustration but not of limitation to exemplify the fabrication of composite heat-fusible material spray wires in accordance with theinvention.

5 Example I' '1- parts; by weight: of 80. mesh metallic chromium powder are mixed with 1.5 parts by weight of polystyrene molding powder. The thoroughly intermixed materials are placed in a screw type extrusion machine wherein the action of the screw thoroughly mixes, kneads and plasticizes the material as it is forced through the various zones of heat at a temperature of about 325 to 500 F. and then to the forming die where it is molded into wire form.

Example N chine, the temperature being maintained therein sufficient to assure plasticity of the mix, which is thereafter extruded through a forming die, thus being molded into wire form.

Example III About 15 parts by weight of di-octyl phthalate are thoroughly mixed with parts of the same chromium-nickel alloy specified in Example II under conditions assuring plasticity, and worked and extruded into wire form as set forth in the preceding examples.

Suitable plasticizing agents may be used if desired. The selection of these depends upon the particular plastic material used. Wax plasticizer have proven satisfactory in many cases. On the other hand, certain plastics, such as those referred to in Examples II and III, are sufficiently flexible and satisfactory composite wires in accordance with the invention are obtained without the necessity of incorporating any plasticizing material.

Wherever the expression wire is used herein the same is intended to include wires of coil length as well as those of less than coil length including rods.

The foregoing specific description is for purposes of illustration and not of limitation and it is therefore my intention that the invention be limited only by the appended claims or their equivalents wherein I have endeavored to claim broadly all inherent novelty.

I claim: J

1. A composite wire for heat-fusible material spray guns of the wire 'feed type comprising a spray gun wire substantially consisting of a heat-fusible non-drawable metal in substantially subdivided form mixed with and held to spray wire shape by a synthetic plastic as a binder sub-- stantially e'liminatable from the metal spray of the gun by the heat of the gun.

2. A composite wire in accordance with claim 1 in which said plastic is one generating at said heat at least one reducing gas.

3. A composite wire in accordance with claim 1, in which said plastic is polystyrene.

4. A composite wire in accordance with claim 1, in which said plastic is a thermoplastic cellulose ester.

5. A composite wire in accordance with claim 1, in which said plastic is a copolymer vinyl ester.

6. A composite wire in accordance with claim 1, in which said plastic is polyethylene.

7. A composite wire in accordance with claim 6 in which said metal is a hard facing chromiumboron-nickel alloy.

CHARLES DAVIDOFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,031,616 Benrath July 2, 1914 1,968,815 Boyden Aug. 7, 1934 2,199,526 McCowen May 7, 1940 2,231,247 Bleakley Feb. 11, 1941 2,261,716 Casto Nov. 4, 1941 2,358,407 McMahon Sept. 19, 1944 2,403,657 Harvey July 9, 1946 2,406,428 Luckhaupt Aug. 27, 1946 FOREIGN PATENTS Number Country Date 234,969 Great Britain June 11, 1925 

1. A COMPOSITE WIRE FOR HEAT-FUSIBLE MATERIAL SPRAY GUNS OF THE WIRE FEED TYPE COMPRISING A SPRAY GUN WIRE SUBSTANTIALLY CONSISTING OF A HEAT-FUSIBLE NON-DRAWABLE METAL IN SUBSTNTIALLY SUBDIVIDED FORM MIXED WITH AND HELD TO SPRAY WIRE SHAPE BY A SYNTHETIC PLASTIC AS A BINDER SUBSTANTIALLY ELIMINATABLE FROM THE METAL SPRAY OF THE GUN BY THE HEAT OF THE GUN. 